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Thread: another LB7 locked ECM

  1. #1
    Member jeeper's Avatar
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    Default another LB7 locked ECM

    Hello. I recently (within the last 2 months) bought a 2004 Silverado LB7 that needed new injectors. I have since replaced the injectors and the truck runs ok now. My problem is I now have a security light on in the dash and the serial number is corrupted. Not only that, I cannot read the ECU with EFILive to even flash the computer. I'm not sure the security light was on when I bought the truck but I'm sure it is now. The truck sat for almost two years before I got it and I know it sat for at least two weeks with no batteries connected.

    I have tried using my V2 to cal flash the ECU but it says the computer is locked with a custom key. It tried over 3200 something keys and it took several hours.

    Also it seems to lose it's prime when it sits overnight. I seem to have to prime the fuel before I start it or it cranks a long time before it will start. But if I prime it it will start quickly and after it runs a few minutes it will fire off immediately when I try to start it after short period shut downs.

    My main concern is the security light. I need to get that sorted first.

    Any suggestions?
    2002 Duramax
    project Jeep Wrangler to CJ conversion with a LS engine and 6L80e transmission underway

  2. #2
    Lifetime Member killerbee's Avatar
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    Quote Originally Posted by jeeper View Post

    My main concern is the security light. I need to get that sorted first.

    Any suggestions?
    I have about a dozen or so LB7 ecms with the same problem. I usually have to replace the ecm for the customer. The first gen has an unknown spontaneous loss of identity issue, and I am not clear what the main cause is. I happy to put it on the bench if you want to ship it off.
    Michael, Systems Engineer 04.5 D-max LLY, Phoenix, Arizona Email
    Custom Tuning Services
    DURAMAX/CUMMINS ECM's TCM's for sale, all years, 20% wholesale discount available
    EFILive's first VGT "Software Wastegate Tune"

  3. #3
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    I'm not too familiar with the diesel stuff. Yeah, for some reason these LB7's fubar the parameters section which corrupts the seed/key, serial # and vin too, basically the entire "block". I can repair them on the bench with my BDM. I'm not sure about the security light. Do you guys have to do a VATS relearn for that when replacing the ecm?

    See also https://service.efilive.com/kb/artic...-gm-gas-diesel
    Last edited by In-Tech; May 31st, 2022 at 01:44 PM.

  4. #4
    Member jeeper's Avatar
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    Quote Originally Posted by In-Tech View Post
    Thanks. I was afraid of that. I'll call Wait4ME Performance tomorrow to see what they can tell me.

    I appreciate the help. And thanks killerbee for the offer to put it on the bench. I'll probably try Wait4Me because they are much closer to home for me.

    I will update this thread as I learn more.
    2002 Duramax
    project Jeep Wrangler to CJ conversion with a LS engine and 6L80e transmission underway

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